[PKT_SCHED]: Make sch_fifo.o available when CONFIG_NET_SCHED is not set.

Based on patch by Patrick McHardy.

Add a new option, NET_SCH_FIFO, which provides a simple fifo qdisc
without requiring CONFIG_NET_SCHED.

The d80211 stack needs a generic fifo qdisc for WME.  At present it
uses net/d80211/fifo_qdisc.c which is functionally equivalent to
sch_fifo.c.  This patch will allow the d80211 stack to remove
net/d80211/fifo_qdisc.c and use sch_fifo.c instead.

Signed-off-by: David Kimdon <david.kimdon@devicescape.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/Kconfig b/net/sched/Kconfig
index b243709..f4544dd 100644
--- a/net/sched/Kconfig
+++ b/net/sched/Kconfig
@@ -6,6 +6,7 @@
 
 config NET_SCHED
 	bool "QoS and/or fair queueing"
+	select NET_SCH_FIFO
 	---help---
 	  When the kernel has several packets to send out over a network
 	  device, it has to decide which ones to send first, which ones to
@@ -40,6 +41,9 @@
 	  The available schedulers are listed in the following questions; you
 	  can say Y to as many as you like. If unsure, say N now.
 
+config NET_SCH_FIFO
+	bool
+
 if NET_SCHED
 
 choice